Separable blade agitator



Feb. 10,1970 .J 'NUNL|$T mL- *3,494,708.-

SEPARABLE BLADE AG-ITATOR' Filed Apri; 2.2, 1968 ATTORNEY United States Patent O 3,494,708 SEPARABLE BLADE AGITATOR Erwin J. Nunlist, Rochester, and John S. Eyster, Fairport,

N.Y., assignors to Ritter Pfaudler Corporation, Rochester, N .Y., a corporation of New York Filed Apr. 22, 1968, Ser. No. 723,023 Int. Cl. B01p 7 00 U.S. Cl. 446-214 9 Claims ABSTRACT F THE DISCLOSURE Apparatus is provided for joining the shaft and blade portions of a separable blade agitator in a uld tight,

gasketless connection wherein a draw bar, moved by hydraulic means through an axial bore in the shaft and against a high spring constant bias has one end adapted to receive the separable blade portions. The blade portions are brought together on the draw bar against the shaft by a draw nut engageable with one end of the draw bar while hydraulic pressure is being exerted on the bar, after which the hydraulic means is released to permit the high spring constant bias to urge the draw bar so as to seat the sealing surfaces of the shaft and separable blade portions one against the other in a duid tight, gasketless connection, after which another fluid under pressure is introduced internally between the draw bar and the blade portions and nut for purposes of detecting leakage at the seal faces.

BACKGROUND OF THE INVENTION The present invention relates to a separable blade agitator and more particularly to a separable blade agitator in which the separable elements of the agitator can be joined together in a fluid tight, gasketless connection and the integrity of the connection tested.

Separable blade agitators have great value in pressure vessels because they circumvent the need for large vessel openings, the separable portions of the agitator being inserted individually into the pressure vessel through a small opening and then assembled within the vessel. Such a separable blade agitator is described in Patent No. 2,811,339 to Osborne et al. The design shown in this patent, wherein gaskets are disposed between all sealing surfaces, has met with only limited success in that it is impossible to avoid leakage with resilient gaskets that are subjected to relatively large temperature and pressure uctuations. That is, it is diicult with the use of a single bolt and manual torque to attain the face loading necessary to maintain the integrity of the seal during relatively large temperature and pressure changes over a period of time. Such designs required frequent retightening causing the gasket to eventually lose its resiliency and fail. Multiple bolt arrangements have been successful in certain situations but space limitations often make the use of multiple bolts impractical. Moreover, in cases wherethe separable portions of the agitator are glass coated, it is diflcult if not impossible to apply a torque to the glassed members with a wrench or similar device as shown in Patent No. 2,811,339 for fear of fracturing the glass coating. Accordingly, other means must be found to mate the blade members of the agitator to the shaft member without the necessity of applying a high torque to any of the glassed members with a wrench or similar device.

Heretofore, it was considered impossible to mate glass coated sealing surfaces in a lluid tight connection without using gaskets of one form or another. It has been found1 however, that glass coated sealing surfaces can be brought together in a uid tight gasket free connection provided certain conditions exist. These conditions are set out 3,494,708 Patented Feb. 10, 1970 ice in greater detail in a copending application, Ser. No. 465,603, filed June 21, 1965, now Patent No. 3,439,940. For purposes of the present invention, it is suicient to say that the conditions that are necessary for effecting a liuid tight, gasketless connection between glass coated surfaces is that these surfaces be 'substantially at and smooth and that the glass coated members be brought together axially in substantially sheer free engagement with a force of approximately 10,000 p.s.i.

Another disadvantage in the prior art is that once the connection has been tmade, there is no effective way of testng the lseal between the shaft and separable blade portions to insure that the gasket fmaterial has made the connection fluid tight. This often leads to failure of the assembly since corrosive material leaking undetected through a defective yet sound-looking gasket attacks the interior of the shaft and blade portions which are not glass coated. In a gasketle-ss jont,where there is no gasketing material to inspect, it is important to provide a system which can be conveniently utilized to check the integrity of the connection.

SUMMARY OF THE INVENTION The present invention can be characterized in one aspect thereof by the provision of a glass coated shaft and separable blade portions, a bore in the shaft having a draw bar slidable therein, bias means normally urging thedraw bar into the bore and hydraulic means for moving the draw bar against the urging of the bias means so that the blade portions can be engaged to the draw bar and butted against the shaft. Release of the hydraulic means causes the draw bar to move under the iniluence of the bias, forceably seating the 'glass coated blade portions together and against the shaft with a force of about 10,000 p.s.i. to effect the gasketless, fluid tight connection. A fluid under pressure is then directed between the bore and draw bar for purposes of checking the integrity of the seal, a poor connection being detected by seepage of the iiuid at the seal face.

OBJECTS OF THE INVENTION The primary object of the present invention is to provide means for joining separable glass coated members together in a gasketless, fluid tight connection.

Another object of the present invention is to provide means for joining together separable glass coated members in a gasketless, uid tight substantially shear free connection.

Yet another object of the present invention is to provide a separable blade agitator wherein bias means are provided for urging the separable blade portions together in a gasketless, fluid tight connection.

A further object of the present invention is to provide a separable blade agitator having means for urging the separable blade portions together in a gasketless, uid tight connection and means for testing the integrity of the fluid tight connection.

Still another object of the present invention is to provide a separable `blade agitator having means for joining the separable blade portions together in a gasketless, fluid tight connection which maintains a relatively constant face loading over a relatively wide range of temperature and pressure changes.

Another object of the present invention is to provide a separable blade agitator having a simple positive fastening means for joining the separable portions together in a uid tight, gasketless connection which may be readily and economically manufactured and which is convenient, reliable and satisfactory in operation.

These and other objects, advantages and characterizing features of the invention will become more apparent upon consideration of the following detailed description thereof in conjunction with the accompanying drawings depicting the same.

DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODHVIENTS Referring to the drawings, FIGURE 1 shows the separable Iblade` agitator assembly generally indicated at to include a shaft portion 8, separable blade portions 14 and cap portion 16. It is preferred that the entire surface of assemly 10* be coated with a continuous layer of vitreous enamel or glass 18 for purposes of protecting the shaft, blade and cap portions from abrasive or corrosive attack by the environment in which the agitator assembly is used.

As shown in FIGURE 2, shaft 8 has a hub portion ,12 provided `Iwith an axial bore 20 therein which opens through one end 22 of the hub. One portion of bore 20 forms a cylinder 21, another portion of the bore forms an enlarged chamber 23 and a portion of the bore is threaded at 24 for purposes set out hereinbelow. Hub 12 has an annular sealing surface 26 provided on end 22 `about the opening of the bore, the sealing surface being formed on an extension of the glass coating 18 on the shaft.

Separable blade portions 14 are each provided with an opening 28 therethrough which can be aligned with the opening to hub bore 20. Each separable blade portion also has an annular sealing surface 30 about the opening 28 therein, the sealing surfaces 30 being formed on the extensions of the glass coating 18 on the blade portions.

Cap portion 16 is provided with a bore 32 opening through only one end 34 of the cap. Bore 32 can align with both openings 28 and the opening to bore 20 and is provided with threads for purposes set out hereinbelow. Cap 16 is also provided with an annular sealing surface 38 about the opening of bore 32, sealing suface 38 being formed on an extension of the glass coating 18 on the cap portion.

'Ihe particular structure of annular sealing surfaces 26, 30 and 38 is set out in greater detail in patent application No. 465,603, led June 21, 1965. It is sufficient for purposes of 'the present invention merely to state that these sealing surfaces are glass coated, annular, narrow, substantially at and smooth and will form a gasketless fluid tight connection when brought together in substantially shear free engagement by an axially applied force` of about 10,000 p.s.i.

In order to draw the cap, shaft and separable blade portions together with an axially applied torque-free force of about 10,000 p.s.i., a connector means generally indicated at 40,is disposed at least partially in the bore 20 of hub 12, the connector means 40 including a drive sleeve 42 which has a threaded portion 46 adapted to engage the threaded portion 24 of bore 20. Sleeve, 42, separable blade portions 14 and hub 12 are all adapted to receive a key 44 which facilitates assembly of the agitator and which permits transmission of torque from the shaft to the blade portions without slippage or shear between the seal surfaces 26 and 30.

Connector means 40 also includes a draw bar 50 slidably mated within drive sleeve 42, the draw bar having its end 52 'within cylinder 21 provided rwith a piston generally indicated at 54. Piston 54 includes a retainer 56 and a cup seal 58 attached to draw bar end 52 by `any suitable means such as nut 60 and follower 62. Retainer 56 is provided with a circumferential groove 64 which forms the seat for an O-ring 66, the O-ring and cup seal together acting to form a fluid tight chamber 68 at the end of cylinder 21. Another O-ring 63 is interposed between retainer 56 and draw bar end 52 to prevent leakage of uid under pressure between the draw bar and retainer.

A shoulder forming spacer 70 is positioned adjacent to the inner end at sleeve 42 for retaining a plurality of disc springs 72 within cylinder 21 and about the draw bar, the disc springs being confined between spacer 70 and retainer 56 so as to urge the draw bar in a direction towards the closed end of cylinder bore 21. Disc springs are well known in the art and it is su'icient for purposes of the present invention to say merely that when a plurality of disc springs 72 are arranged in a stack as shown in FIGURE 2, the stack will provide a relatively large loading with a relatively small deflection.

In order to move piston 54 and therefore draw bar 50 against the bias of disc springs 72, hub 12 is provided with a passage 86 which communicates through hub 12 with chamber 68 for introducing hydraulic uid or the like into the chamber. The shaft also is provided with a second passage 88 which communicates with passage 86 and which opens into the enlarged chamber 23 of bore 20 adjacent sleeve 42 for purposes set out hereinbelow. A rst plug 89, threaded to passage 86, seals chamber 68 and a secondremovable plug 90 seals passage 88 from the environment in which the agitator assembly is used.

Draw bar 50 has its other end 80 provided with a ange 82 which bears against a cap sleeve 84, threaded for engagement with cap 16. Flange 82 and cap sleeve l84 together form a conventional conical-to-spherical bearing which permits the cap sleve to rock on ange 82 so as to align sealing surfaces 26, 30 and 38 one against another in face to face relationship. Any suitable means such as pin 83 can be used to prevent the rotation of cap sleeve 84 relative to draw bar 50'.

OPERATION In operation the agitator assembly is rst assembled by extending connector means 40 through agitator blade openings 28, threading sleeve 42 to bore 20 and then threading cap portion 16 to cap sleeve 84. Chamber 68 is then pressurized by introducing hydraulic iluid into the chamber through passage 86. Pressurizing chamber 68 drives piston 54 and therefore draw bolt 50 against the bias of disc sprin-gs 72 which loosens the relationship between the shaft, cap and separable blade portions. Cap portion 16 now can 4be hand turned with very little effort in order to move the cap relative to cap sleeve l84, bringing blade portions 14 and hub 12 together so as to butt the sealing surfaces 26, 30 and 38 one against another. Hand turning cap portion 16 prevents the application of an excessive torque to the cap which in turn eliminates the danger of destroying the glass coated sealing surfaces by shearing one surface over the other.

When hydraulic pressure is removed to depressurize chamber 68, the compressed disc springs 72 expand, drawing bolt 50 into Ibore 20 to forceably seat sealing surfaces 26, 30 and 38 togetherV with an axially applied force of about 10,000 p.s.i. thereby effecting a fluid tight gasketless seal between the sealing surfaces. Should any large temperature or pressure changes occur in the environment in which the agitator is used, the resiliency of disc springs 72 can compensate for any resulting deformation in the draw bar to maintain the required sealing force of approximately 10,000 p.s.i. at the seal faces. Very little deformation of the stack of disc springs 72 is required to maintain the required sealing force because there is no need to compensate for the yielding of a gasket material between the seal faces.

Once the cap, separable blade portions and shaft have been brought together in a gasketless, uid tight connection, plug 89 is inserted into passage 86 to seal chamber 68 and any suitable fluid under pressure, such as air or a colored low viscosity fluid, can be directed into passage 88. This iluid under pressure passes through passage 88 into bore 20 and over sleeve 42 to ll the spaces 92 immediately behind the connection between sealed surfaces 26, 30 and 38. In this manner any defective joint will be detected by seepage of the uid at the seal face. After the integrity of the joint has been checked, plug 90 is inserted prevent the environment in which the agitator is used from entering the interior of the agitator assembly through passages 86 and 88.

FIGURE 2 also shows a feature of the invention which will permit a periodical check on the integrity of the seal even While the seal is in use. In this respect, passage 88 can also communicate with bore 94 extending axially through shaft 8 to communicate with any suitable pressurizing means such as a compressed air supply, not shown, which lies outside of the environment in which the agitator is used. Plug 90 has a groove 96 therein to permit pressurized air in bore 94 to enter through passage 88 to the spaces 92 immediately adjacent the seal surfaces. With this arrangement, the integrity of the seal can be checked while the agitator blade is in use simply by applying pressure and watching for the escape of bubbles or pressurizing fluid from between the seal faces.

Referring now to the embodiment shown schematically in FIGURE 3, it should bel apparent that this embodiment has structure that is similar to the structure of the embodiment shown in FIGURES l and 2. Accordingly, when referring to FIGURE 3, like structure will be designated by the prime of like reference numerals. The embodiment shown in FIGURE 3 shows a cap portion 98 made as an integral part of one of the separable blades 14'. In this respect, cap 98 is provided with an internal thread 100 which is adapted to mate with corresponding threads formed on the end 80' of draw bar 50'. Thus, when draw bar 50 is moved so as to loosen the assembly in a manner set out hereinabove, the separable blade and cap portion 98 can be threaded to the draw bar and rotated. Rotation of cap 98 draws hub 12', and separable blade portions 14 together so as to butt sealing surfaces 26', 30 and 38 one against the other. The necessary force of 10,000 p.s.i. is then applied to the separable components to bring the sealing surfaces into a gasketless fluid tight connection in a manner set out hereinabove.

Thus, it will be appreciated that the present invention accomplishes its intended objects providing a means for joining the separable blade portions of a separable blade agitator in a gasketless, iuid tight and shear free connection and the means for maintaining a continuous check on the integrity of the connection.

While we have described only two embodiments of our invention, it should be apparent that various modications can be made therein without changing the scope of the invention as claimed. For example, if draw bar 50 were sufficiently long the draw bar could be heated prior to drawing the separable portions together so that contraction of the bar upon cooling would supply the required face loading of 10,000 p.s.i. In such a situation, the elastic deformation of the draw bar would be sufcient to compensate for any pressure or temperature changes of the environment to maintain the required face loading. Furthermore, While the preferred embodiments have the sealing surfaces glass coated, it should be obvious to one skilled in the art that the present invention can also be used to mate surfaces which are not glass coated in a gasketless, fluid tight connection.

Having thus decribed our invention in detail, what we claim as new is:

1. A separable blade agitator comprising:

(a) a shaft member having a bore therein opening 6 through one end of said shaft and an annular sealing surface on said one end about said bore open- 111g;

(b) a separable blade member having a bore therethrough and an annular sealing surface about each opening of said bore;

(c) connector means slidably extending through said blade member bore and into said shaft member bore;

, (d) resilient means normally urging said connector means into said shaft member bore;

(e) means for actuating said resilient means; and

(f) adjustable means engageable with said connector means for drawing said shaft and blade members together to abut said sealing surfaces one against another when said resilient means is actuated, wherelby said connector means is moved axially by said resilient means to force said abutting sealing surfaces into shear free uid tight engagement when said actuating means is released.

2. A separable blade agitator comprising:

(a) a shaft member having a longitudinal bore and a sealing surface surrounding the opening of said bore;

(b) a separable blade member having a longitudinal 'bore and a sealing surface surrounding the opening of said bore;

(c) a draw bar extending through said blade member bore and into said shaft member bore;

(d) adjustable means engaging said draw bar for drawing said shaft and separable blade members together to abut said sealing surfaces one against another;

(e) resilient means operatively connected to Said draW bar for urging said draw bar and therefore said adjustable means toward said shaft to seat said sealing surfces one against another in a fluid tight relationship; and

(f) means for compressing said resilient means to permit said adjustable means to draw said shaft and separable blade members together.

v 3. The apparatus as set forth in claim 2 in which the end of said draw bar in said shaft member bore carries piston means slidably sealed with the wall of said bore to form a fluid tight chamber at one end of said bore.

4. The Iapparatus as set forth in claim 3 in which said shaft member has a passage therein communicating with said chamber for purposes of introducing a pressurizing fluid into said chamber, to move said piston and therefore said draw bar against said resilient means and toward said bore opening.

5. The apparatus as set forth in claim 3 further comprising a sleeve member having one end xed within said bore and a second end extending out of said bore, said second end being adapted to carry said separable blade portions and said rst end being adapted to support said resilient means.

6. Apparatus as set forth in claim 5 in which said resilient means comprises a plurality of disc springs disposed about said draw bar and between said shoulder and said piston for urging said piston and therefore said draw bar in a direction into said bore.

7. Apparatus as set forth in claim 5 further corn-prising seal testing means in said shaft member for directing fluid under pressure through said bore, about said sleeve and to said sealing surfaces.

8. Apparatus as set forth in claim 7 in which said seal testing means comprises a passage in said shaft communicating with said bore and means for introducing a tluid under pressure to said passage.

9. Apparatus as set forth in claim 2 in which said shaft, separable blade and cap portions are provided with a 3,494,708 7 8 corrosion resisting glass coating, said annular sealing sur- WILLIAM I. PRICE, Primary Examiner faces being an extension of said glass coating. U s C1 XR References Cited 259-1; 285-18, 93; 416-244 UNITED STATES PATENTS 5 2,811,339 10/1957 Osborne et al. 259-134 

